A process for improving the flavour of potato is known from U.S. Pat. No. 3,814,818 by preparing an edible oil composition, which oil composition is prepared by adding 0.001-4.0% by weight methionine to an oil and heating the oil to 120.degree.-220.degree. C. It might be preferred according to that U.S. patent to further add a reducing sugar in an amount of 1-25% by weight of said methionine. At all event, the end product is an oil mixture in which the potato can be fried. According to the invention, the flavour is prepared without using the oil by reacting the starting materials for the flavour product at an elevated temperature after which the potato product is treated with the preferably aqueous solution of the processed flavour mixture so that a surface layer containing an effective amount of the processed flavour mixture is present on the potato product.
From U.S. Pat. No. 2,589,591, a method for controlling color and flavour of potato chips is known in which the potato is immersed in an aqueous solution of a reducing sugar and a protein hydrolyzate derived from raw potatoes. The protein hydrolyzate gives a number of amino acids and an example of such a mixture is given in Column 3, lines 4-16 of the above-mentioned U.S. patent indicating 13 different amino acids.